The present invention is related to an asphalt composition and its preparation process. More particularly, it is related to a storage-stable polymer-modified asphalt composition and its preparation process.
Asphalt materials have rapidly developed as paving and decorating materials in the road and architecture sectors. However, the optimum performance properties of asphalt and its blend such as viscoelasticity, plasticity, adhesiveness, etc. can not exert since they are affected by many factors. Among various factors, climate is the most important one. In the season of high temperature, summer, ruts caused by racing vehicles on express highways are the major factor leading to the damage of the road surface. In winters, fractures on the road surface resulted from the abruptly change of the temperature are the major causes for the transverse crack. In the rain seasons in the south, the intrusion of the rainwater leads to the interaction of asphalt with the blend material at the interface, thereby lowering the adhesive performance of asphalt and making it easy for asphalt to strip from the stones. Therefore, it is necessary to improve the Theological property of asphalt. Addition of a polymer is an effective way to improve the performance of asphalt. Addition of a polymer can enhance the viscosity and high temperature resistance, lower the low temperature sensibility, and improve the low temperature performance at the same time.
Asphalt modified by olefin polymers is reviewed in T. F. Yen, et al., Asphaltenes and Asphalts, I Developments in Petroleum Science. The amount of the polymers is 6 wt %, and the stability of asphalt modified by various polymers is shown in Table 1.
It can be seen from Table 1 that when APP (atactic polypropylene), LDPE (low density polyactene), EPDM (ethylenepropylene-diene ternary copolymer), SBS (styrene-butadiene-styrene three-block copolymer) are added to asphalt respectively, phase separation takes place between most of the polymers and asphalt, thus directly affecting the performance properties of the asphalt-polymer compositions.
EP 639630A1 discloses a process for preparing stable asphalt-polymer compositions, wherein a raw asphalt with a certain constitution is first screened as the raw material of the modified asphalt, and then reacted with the three block polymer SBS as a polymer modifier and a vinyl aromatic (such as styrene) as an assistant added thereto in an inert environment to yield a sample with good stable performance. There is a limit to the source of the raw material of the modified asphalt in this process, and styrene as an assistant is of no help in the dispersion of SBS in asphalt. In addition, the reaction cost increases since a nitrogen environment is needed.
U.S. Pat. Nos. 5,336,705, 5,627,225, and 5,348,994 first use fuming sulfuric acid or other sulfonating reagent to sulfonate the raw asphalt and the polymer modifier to incorporate acidic groups into both of them, and then neutralize with alkalis such as CaO, ZnO, etc. as neutralization reagents. This process prolongs the preparation process, increases the production cost, and results in corrosion of the apparatus by sulfonating reagents.
U.S. Pat. No. 5,306,750 discloses a process for reacting a polymer with asphalt, and a polymer-linked-asphalt product. This process is to covalently react 0.05-2 wt % of an epoxide-containing polymer with asphalt at a temperature above 100xc2x0 C. for longer than 1 h. No phase separation happened with the modified asphalt obtained by this process after storing in a drying oven at 163xc2x0 C.-177xc2x0 C. for 4 days.
U.S. Pat. No. 5,331,028 discloses a polymer-modified asphalt composition and its preparation process. The constitution of the composition is that the reaction product derived by the reaction between 100 parts by weight of asphalt and 0.5-11 parts by weight of an ethylene copolymer containing glycidyl accounts for 80-99.7 wt %, and that the styrene/conjugated diene block copolymer accounts for 0.3-20 wt %. The process is to mix 70-99.2 wt % of asphalt, 0.5-10 wt % of the ethylene copolymer containing glycidyl, and 0.3-20 wt % of a styrene/conjugated diene block copolymer, and to react at 170xc2x0 C.-220xc2x0 C. for 6-36 h to yield a reaction product.
Although the compatibility of the polymer with asphalt used in U.S. Pat. Nos. 5,331,028 and 5,306,750 is rather good, the high preparation cost of the polymer and the difficulty in reaction are the major control factors.
One of the objectives of the present invention is to provide a storage-stable modified asphalt composition.
Another objective of the present invention is to provide a process for preparing the storage-stable modified asphalt composition.
The present invention provides a storage-stable modified asphalt composition, which comprises:
and the softening point difference of its product determined by the stability test is lower than 2.5xc2x0 C.
The present invention also provides a process for preparing the storage-stable modified asphalt composition, which comprises mixing 50-97.7 parts by weight of a base asphalt, a 2.0-20.0 parts by weight of a polymer having double bonds, 0.1-20.0 parts by weight of a compatibilizer, 0.1-10.0 parts by weight of a cross-linking reagent, and 0.1-10.0 parts by weight of a organic polar compound under certain conditions.
The present invention provides a storage-stable modified asphalt composition, which comprises:
and the softening point difference of its product determined by the stability test is lower than 2.5xc2x0 C.
Said base asphalt is one selected from the group consisting of petroleum asphalts, coal-tar asphalts, tar sand asphalts and native asphalts, or a mixture thereof, wherein the petroleum asphalt is one selected from the group consisting of straight-run asphalts, asphalts obtained by solvent deasphalting, oxidized asphalts, and blended asphalts, or a mixture thereof. Said straight-run asphalt is an atmospheric residue or vacuum residue obtained through atmospheric distillation or vacuum distillation, the Penetration of which at 25xc2x0 C. is 20-300 dmm (i.e. {fraction (1/10)}mm). Said asphalt obtained by solvent deasphalting is a deoiled asphalt obtained by extracting a residue with one of the C3-C5 hydrocarbons or their mixtures. The Penetration of the deoiled asphalt at 25xc2x0 C. is 5-200 dmm.
Said polymer having double bonds is a block polymer of styrene-butadiene in a ratio of 20-45:80-55 which mainly refers to the SBS type. The structure of SBS is star or linear, the molecular weight of which is in the range of 100,000 to 350,000. The block polymer can be either a dry rubber, or an oil-extended polymer wherein 2-60 wt % weight of oil is extended.
Said compatibilizer is one selected from the group consisting of styrene tar, tall oil, acid-containing tall oil, catalytically cracked oil slurry, heavy deasphalted oil, extracted oil obtained by solvent refining, naphthenic acid, naphthenic oil, white oil, and coal tar fractions, or a mixture thereof.
Said cross-linking reagent is one selected from the group consisting of crystallized sulfurs, activated sulfurs, sulfur-donors, and xe2x80x9csymbolizingxe2x80x9d sulfur-donating cross-linking reagents, or a mixture thereof. Said activated sulfur is a sulfur powder, a colloidal sulfur, or a mixture thereof. Said colloidal sulfur is a colloid with an average diameter of 1-5 xcexcm prepared by mixing sulfur powder or precipitated sulfur with a dispersion reagent and then grinding. The sulfur donor is one selected from the group consisting of sulfur-containing morpholinium compounds, thiuram compounds, and polysulfides, or a mixture thereof.
The general formula of the thiuram compounds is: 
wherein x=1-4, R1, R2, R3, and R4: a C1-C4 alkyl.
Polysulfides: R1xe2x80x94(S)nxe2x80x94R2, R1, R2 is a aliphatic or aromatic heterocyclic group, such as cycloheptathiaimine alkylphenol, alkylphenol monosulfide.
Said xe2x80x9csymbolizingxe2x80x9d sulfur-donating cross-linking reagent mainly refers to a metal oxide cross-linking reagent, wherein the metal manly refers to a divalent metal such as Ca, Mg, Zn or Pb, etc. Said xe2x80x9csymbolizingxe2x80x9d sulfur-donating cross-linking reagent is one selected from the group consisting of CaO, MgO, ZnO, and PbO, or a mixture thereof.
Said organic polar compound mainly refers to a compound with polar groups, which is one selected from the group consisting of amine, acid, phenolic resin and aldehyde compounds, or a mixture thereof
Said amine compounds mainly refer to aliphatic amine and aromatic amine compounds which is one selected from polyactene polyamine compounds, wherein the polyactene comprises di-, tri- and tetraethylene; and the polyamine comprises hexamethylene diamine, tetramine, penta-amine, or a mixture thereof.
Said acid compound is one selected from the group consisting of carboxylic acid, acid anhydride, sulfonic acid, boric acid, and phosphoric acid compounds, or a mixture thereof.
Said carboxylic acid compound is one selected from the group consisting of aliphatic acids and aromatic acids, or a mixture thereof.
Said acid anhydride compounds are phthalic anhydride and its derivatives or maleic anhydride and its derivatives.
The general formula of said sulfonic compounds is: 
wherein R1, R2, and R3H or a C1-C5 alkyl.
Said phosphoric acid compound is one selected from polyphosphoric acid, phosphorous acid, modified polyphosphoric acid, and phosphate compounds, or a mixture thereof.
Said phenolic resin compound is one selected from formaldehyde alkylphenol resin compounds, wherein the alkyl is p-tert-butyl or p-tert-octyl paraffinic group. The polar hetero-atom containing alkyl is also desired, wherein said formaldehyde alkylphenol resin comprises formaldehyde phenol resin having sulfur or oxygen atom containing alkyl.
Said aldehyde compound is one selected from glycidic aldehyde, formaldehyde, binary aldehydes, and furfural, or a mixture thereof, wherein the binary aldehydes are p-phthalic aldehyde and its derivatives or m-phthalic aldehyde and its derivatives.
The present invention also provides the process for preparing a storage-stable modified asphalt composition, which comprises: mixing 50-97.7 parts by weight of a base asphalt, 2.0-20.0 parts by weight of a polymer having double bonds, 0.1-20.0 parts by weight of a compatibilizer, 0.1-10.0 parts by weight of a cross-linking reagent, and 0.1-10.0 parts by weight of a organic polar compound under certain conditions.
Said compatibilizer can be first mixed with the base asphalt, or with the polymer having double bonds, or with the mixture of the polymer having double bonds and the base asphalt; or said compatibilizer can be added at last, said compatibilizer can be added either once or twice. Said base asphalt can also be added either once or twice.
Mixing of various components can be static, dynamic, grinding, or vigorous stirring.
The process provided by the present invention will be illustrated below with four embodiments, but the process provided by the present invention is not limited to the three embodiments.
Embodiment 1:
The process provided by the present invention comprises the following steps:
(1) contacting the base asphalt with the compatibilizer at 100xc2x0 C.-250xc2x0 C. for 0.1-6 h to yield the treated base asphalt;
(2) mixing the treated base asphalt with the polymer having double bonds for 0.1-10 h to yield the asphalt mother liquor,
(3) adding the cross-linking reagent, organic polar compound, and optional base asphalt to the asphalt mother liquor at 100xc2x0 C.-250xc2x0 C. to react for 5-300 min, yielding the modified asphalt composition.
In this embodiment, said base asphalt, polymer having double bonds, compatibilizer, cross-linking reagent, and organic polar compound account for 50-97.7 parts by weight, 2.0-20.0 parts by weight, 0.1-20.0 parts by weight, 0.1-10.0 parts by weight, and 0.1-10.0 parts by weight of the modified asphalt composition, respectively. The weight ratio of the base asphalt in step (3) to that in step (1) is 0-50:100-50.
Embodiment 2:
The process provided by the present invention comprises the following steps:
(1) contacting the base asphalt with the compatibilizer at 100xc2x0 C.-250xc2x0 C. for 0.1-6 h to yield the treated base asphalt;
(2) mixing the treated base asphalt with the polymer having double bonds for 0.1-10 h to yield the asphalt mother liquor,
(3) adding the cross-linking reagent, organic polar compound, and optional compatibilizer to the asphalt mother liquor at 100xc2x0 C.-250xc2x0 C. to react for 5-300 min, yielding the modified asphalt composition.
In this embodiment, said base asphalt, polymer having double bonds, compatibilizer cross-linking reagent, and organic polar compound account for 50-97.7 parts by weight, 2.0-20.0 parts by weight, 0.1-20.0 parts by weight, 0.1-10.0 parts by weight, and 0.1-10.0 parts by weight of the modified asphalt composition. The weight ratio of the compatibilizer in step (3) to that in step (1) is 0-50:100-50.
Embodiment 3:
The process provided by the present invention comprises the following steps:
(1) mixing the base asphalt at 100xc2x0 C.-250xc2x0 C. with the polymer having double bonds for 0.1-10 h to yield the asphalt mother liquor;
(2) contacting the asphalt mother liquor at 100xc2x0 C.-250xc2x0 C. with the compatibilizer at 100-250xc2x0 C. for 0.1-6 h to yield the treated asphalt mother liquor;
(3) adding the cross-linking reagent, organic polar compound, and the optional base asphalt to the treated asphalt mother liquor to react for 5-300 min, yielding the modified asphalt composition.
In this embodiment, said base asphalt, polymer having double bonds, compatibilizer, cross-linking reagent, and organic polar compound account for 50-97.7 parts by weight, 2.0-20.0 parts by weight, 0.1-20.0 parts by weight, 0.1-10.0 parts by weight, and 0.1-10.0 parts by weight of the modified asphalt composition, respectively. The weight ratio of the base asphalt in step (3) to that in step (1) is 0-50:100-50.
Embodiment 4:
The process provided by the present invention comprises the following steps:
(1) contacting 2.0-20.0 parts by weight of a polymer having double bonds with 0.1-20.0 parts by weight of a, compatibilizer at 10xc2x0 C.-250xc2x0 C. for 0.1-72 h to yield the treated polymer having double bonds;
(2) heating 50-97.7 parts by weight of the base asphalt to 100xc2x0 C.-250xc2x0 C.;
(3) mixing the treated polymer having double bonds with the heated base asphalt for 0.1-6.0 h to yield an asphalt mother liquor, and maintaining the temperature of the asphalt mother liquor at 100xc2x0 C.-250xc2x0 C.;
(4) adding 0.1-10.0 parts by weight of the cross-linking reagent and 0.1-10.0 parts by weight of the organic polar compound into the asphalt mother liquor to react for 5-300 min, yielding the modified asphalt composition.
Said base asphalt in the aforesaid process is one selected from the group consisting of petroleum asphalts, coal-tar asphalts, tar sand asphalts and native asphalts, or a mixture thereof, wherein the petroleum asphalt is one selected from the group consisting of straight-run asphalts, asphalts obtained by solvent deasphalting, oxidized asphalts, and blended asphalts, or a mixture thereof The straight-run asphalt is an atmospheric residue or vacuum residue obtained through atmospheric distillation or vacuum distillation, the Penetration of which at 25xc2x0 C. is 20-300 dmm (i.e. {fraction (1/10)} mm). The asphalt obtained by solvent deasphalting is a deoiled asphalt obtained by extracting a residue with one of the C3-C5 hydrocarbons or their mixtures. The Penetration of the deoiled asphalt at 25xc2x0 C. is 5-200 dmm.
Said polymer having double bonds is a block polymer of styrene-butadiene in a ratio of 20-45:80-55, which mainly refers to the SBS polymers. The structure of the SBS is the star or linear, the molecular weight of which is in the range of 100,000 to 350,000. The block polymer can be either a dry rubber, or an oil-extended polymer wherein 2-60 wt % of oil is extended.
Said compatibilizer is one selected from the group consisting of styrene tar, tall oil, acid-containing tall oil, catalytically cracked oil slurry, heavy deasphalted oil, extracted oil obtained by solvent refining, naphthenic acid, naphthenic oil, white oil, and coal tar fractions, or a mixture thereof.
The addition of the compatibilizer into the system can enhance the compatibility of the polymer in asphalt. Since the compatibilizer itself has good intersolubility with both the polymer and asphalt, it can increase the compatibility with both.
Said cross-linking reagent is one selected from the group consisting of crystallized sulfurs, activated sulfurs, sulfur-donors, and xe2x80x9csymbolizingxe2x80x9d sulfur-donating cross-linking reagents, or a mixture thereof Said activated sulfur is a sulfur powder, a colloidal sulfur, or a mixture thereof. Said colloidal sulfur is a colloid with an average diameter of 1-5 xcexcm prepared by mixing sulfur powder or precipitated sulfur with a dispersion reagent and then grinding. The sulfur donor is one selected from the group consisting of sulfur-containing morpholinium compounds, thiuram compounds, and polysulfides, or a mixture thereof.
The general formula of the thiuram type compounds is: 
wherein x=1-4, R1, R2, R3, and R4: a C1-C4 alkyl.
Polysulfides: R1xe2x80x94(S)nxe2x80x94R2, R1, R2 is a aliphatic or aromatic heterocyclic group, such as cycloheptathiaimine alkylphenol, alkylphenol monosulfide.
The xe2x80x9csymbolizingxe2x80x9d sulfur-donating cross-linking reagent mainly refers to a metal oxide cross-linking reagent, wherein the metal manly refers to a divalent metal such as Ca, Mg, Zn, Pb, etc. Said xe2x80x9csymbolizingxe2x80x9d sulfur-donating cross-linking reagent is one selected from one of the group consisting of CaO, MgO, ZnO, and PbO, or a mixture thereof.
The addition of the cross-linking reagent during the mixing of the asphalt/polymer mother liquor permits the polymer in a good dispersion state to carry out the linking reaction with the organic polar compound in asphalt. Thus the polymer can exist in a stable network structure, and the further aggregation and stability of the polymer are prevented
Said organic polar compound mainly refers to a compound with polar groups, which is one selected from the group consisting of amine, acid, phenolic resin and aldehyde compounds, or a mixture thereof
Said amine compounds mainly refer to aliphatic amine and aromatic amine compounds which is one selected from polyactene polyamine compounds, wherein the polyactene comprises di-, tri- and tetraethylene; and the polyamine comprises hexamethylene diamine, tetramine, penta-amine, or a mixture thereof.
Said acid compound is one selected from the group consisting of carboxylic acid, acid anhydride, sulfonic acid, boric acid, and phosphoric acid compounds, or a mixture thereof.
Said carboxylic acid compound is one selected from the group consisting of aliphatic acids and aromatic acids, or a mixture thereof.
Said acid anhydride compounds are phthalic anhydride and its derivatives or maleic anhydride and its derivatives.
The general formula of said sulfonic compounds is: 
R1, R2, R3=H or a C1-C5 alkyl.
Said phosphoric acid compound is one selected from polyphosphoric acid, phosphorous acid, modified polyphosphoric acid, and phosphate compounds, or a mixture thereof.
Said phenolic resin compound is one selected from formaldehyde alkylphenol resin compounds, wherein the alkyl is p-tert-butyl or p-tert-octyl paraffinic group. The polar hetero-atom containing alkyl is also desired, wherein said formaldehyde alkylphenol resin comprises formaldehyde phenol resin having sulfur or oxygen atom containing alkyl.
Said aldehyde compound is one selected from the group consisting of glycidic aldehyde, formaldehyde, binary aldehydes, and furfural, or a mixture thereof, wherein the binary aldehydes are p-phthalic aldehyde and its derivatives or m-phthalic aldehyde and its derivatives.
The function of adding organic polar compounds in the present system is to promote the reaction of the cross-linking reagent. The results of present invention shows that the addition of the organic polar compounds makes the asphalt and the polymer having double bonds form a continuous phase structure through the action of the organic polar compounds.
The modified asphalt composition prepared by the process provided by the present invention has good storage-stability, its softening point difference determined by the stability method being lower than 2.5xc2x0 C. The preparation process provided by the present invention is simple and needs no special apparatus. The modified asphalt composition can be directly used in rainy and wet areas without using anti-stripping reagents to increase the adhesive capability between the stone and asphalt since it has a high viscosity, adhesives, and strong wrap ability for stone. The modified asphalt composition prepared by the process provided by the present invention can also be used as a basic raw material of emulsified asphalt, which may be realized by adding a certain proportion of water and an emulsifier.